linux 系统调用sysconf【总结】【转】

转自：https://www.cnblogs.com/anker/p/3751369.html

1、前言

　　当前计算机都是多核的，linux2.6提供了进程绑定cpu功能，将进程指定到某个core上执行，方便管理进程。linux提供了sysconf系统调用可以获取系统的cpu个数和可用的cpu个数。

2、sysconf 函数

　　man一下sysconf，解释这个函数用来获取系统执行的配置信息。例如页大小、最大页数、cpu个数、打开句柄的最大个数等等。详细说明可以参考man。

3、测试程序

　　写一个测试程序，方便日后使用。

#include <stdio.h>
#include <unistd.h>

#define ONE_MB (1024 * 1024)

int main()
{
    printf("The number of processors configured is :%ld\n",
        sysconf(_SC_NPROCESSORS_CONF));
    printf("The number of processors currently online (available) is :%ld\n",
        sysconf(_SC_NPROCESSORS_ONLN));
    printf ("The pagesize: %ld\n", sysconf(_SC_PAGESIZE));  
    printf ("The number of pages: %ld\n", sysconf(_SC_PHYS_PAGES));  
    printf ("The number of available pages: %ld\n", sysconf(_SC_AVPHYS_PAGES)); 
    printf ("The memory size: %lld MB\n", 
        (long long)sysconf(_SC_PAGESIZE) * (long long)sysconf(_SC_PHYS_PAGES) / ONE_MB );  
    printf ("The number of files max opened:: %ld\n", sysconf(_SC_OPEN_MAX));  
    printf("The number of ticks per second: %ld\n", sysconf(_SC_CLK_TCK));  
    printf ("The max length of host name: %ld\n", sysconf(_SC_HOST_NAME_MAX));  
    printf ("The max length of login name: %ld\n", sysconf(_SC_LOGIN_NAME_MAX)); 
    return 0;
}

我的虚拟机配置了4个核，1G的内存，32位的linux。执行结果如下：